Method for preparation of cyclic organohydrosiloxanes



United States Patent 3,484,468 Patented Dec. 16, 1969 3 484,468 To be more specific, reference is made to the following 9 METHOD FOR PREPARATION OF CYCLIC examples- ORGANOHYDROSILOXANES Example I James W. Curry, Dallas, Tex., assignor to Texas Instrumeats Incorporated Dallas, Tex a corporation f 5 To a three necked separatory funnel maintained at am- D I b1ent temperature and vented to the atmosphere through No Drawing. Filed June 16, 1967, Ser. No. 646,487 a condenser attached to one of the necks was added 222.4 Int. Cl. C07d 103/02; C07f 7/02 grams (3.00 moles) of tert-butyl alcohol [(CH COH] 260-4483 5 Claims and 1 liter of benzene solvent. Through an addition fun- 10 nel carried by another neck of the separatory funnel,

ABSTRACT OF THE DISCLOSURE Reacting a tertiary alcohol such as tert-butyl alcohol [(CH COH] with an organohydrohalosilane such as methyldichlorosilane [CH SiI-ICl to produce cyclic organohydrosiloxanes such as methylhydrosiloxanes having an SiH bond.

there was added 172.6 (1.50 moles) of methyldichlorosilane (CH SiI-ICI The methyldichlorosilane was added dropwise over a 6 hour period while the solution in the separatory funnel was stirred by a motor driven stirring rod suspended through the third neck of the separatory funnel. The solution in the separatory funnel was permitted to set for 60 hours to permit an aqueous layer to separate from the organic layer. While the solution was allowed to set for 60 hours in this instance, 12 hours or possibly less would be quite sufficient. The organic layer (1289.5 grams) was separated and placed in a distillation flask. The benzene solvent and 254.1 grams of tertbutyl chloride were removed by raising the head temperature of the flask to 79.5 C. at atmospheric pressure (743.1-747.0 mm. Hg).

The cyclic species of methylhydrosiloxane were then distilled commencing with a head temperature of C. and a pressure of 25 mm. Hg and ending with a head temperature of 72 C. and a pressure of .05 mm. Hg. Table I details the results of distillation.

TABLE I As percent, As percent As percent based on Grams of total of distillable MBSlHClz Cyclic species or fraction recovered siloxane siloxane used (MeSiHO)4 19.1 21. 7 32. 8 21. 3 EMeSiHOk. 28. 0 31. 8 48.1 31. 2 MeSiHOML 9. 2 10. 5 15. 8 10. 2 (MeSiH0)1 (impure) 1. 0 1. 2 1. 7 1. 1 Combined intermediate fractions.. 0. 9 1. 0 1. 6 1. 0

Total distillables 58. 2 66. 2 Residue 29. 8 33. 8 33. 2

Overall totals 100. 0 100. o 98.7)

cleaved by the HCl formed as a by-product of the reaction. Cleavage of the SiH bond will produce a sili- The physical and analytical data relating to the products of distillation and the residue is detailed in Table H.

TABLE II Molecular Weight Specific refractlvity, R Cyclic species or Befractwe Density, fraction Calcd. Found index, rin at Calcd. Found (MeSiHOh 240. 5 242. 0 1. 3850-1. 3851 0. 9852 0. 2382 0. 2379 (MeSiHO) 300. 7 304. 6 1. 3899-1. 3901 0. 0963 0. 2882 0, 2379 EMeSiHO); 360. 8 360. 0 1. 39294. 3931 l. 0080 0. 2382 0. 2370 MeSiHO) (impure). 420. 9 1. 39 0. 2382 Residue 1, 752 1. 4001 l. 0388 0. 2382 0. 2334 cone gel. The production of the gel may be illustrated by the following equation:

In the above reaction, which may be described by the following equation:

H MeSiHCl +2(CH COH- l Him omsiom +211 01 +112 -MeS1HO-}+2(CH CCl-|-H O a side reaction involving the tert-butyl chloride occurs to a limited extent, giving a small amount of HCl. However, due to solubility considerations, the acid is confined almost exclusively to the aqueous phase and therefore has no efliect on the methylhydrosiloxanes in the organic layer. This is demonstrated by the fact that the final distillation residue, after removal of all volatile cyclics, consists of liquid only, and not solid gel.

In the above reactions, various tertiary alcohols may be used, although tert-butyl alcohol is preferred. For eX- ample, 3 methyl-3-pentanol, 2,3-dimethyl-2-butanol, 2- methyl-Z-pentanol, tert-amyl alcohol, 2-methyl-3-buten-2- 01, and triphenylcarbinol may be used, as well as any of the tertiary alcohols having a lower alkyl, lower alkenyl,

lower alkynyl, or aryl radicals attached to the COH group.

In addition to methyldichlorosilane, other organohydrodihalosilanes such as ethyldichlorosilane, phenyl clichlorosilane, vinyldichlorosilane, ethynyldichlorosilane, propargyldichlorosilane, chlorophenyldichlorosilane, alpha-naphthyldichlorosilane, and other organohydrosilanes having lower alkyl, lower alkenyl, lower alkynyl, or aryl radicals attached to the silane molecule may be used.

Further, while the reaction is preferably carried out in benzene, any suitable non-reactive solvent may be used, such as toluene, pentane, hexane or cyclohexane.

The cyclic organosiloxanes produced by the present invention may be utilized in the same manner as those produced by the prior art method of preparation. The compounds may be reacted as follows:

1. The process of preparing cyclic organohydrosiloxanes, comprising the step of reacting a tertiary alcohol with an organohydrodihalosilane, where halo is selected from the group consisting of chlorine, bromine, and iodine, and where organo is a radical selected from the group consisting of lower alkyl, lower alkenyl, lower alkynyl, and aryl.

2. The process of claim 1, wherein said reaction is carried out in solution with an organic solvent, and said process includes the steps of:

with an organohydrohalosilan'e having the formula R SiHX where: R,,, R R and R are selected independently from a group consisting of a lower alkyl, a lower alkenyl, a lower alkynyl, and an aryl, and X is selected from the group consisting of chlorine, bromine and iodine.

4. The process of claim 3, wherein said tertiary alcohol is tertiary butyl alcohol and said organohydrohalosilane is methyldichlorosilane.

5. The process of claim 4, wherein said process is carried out in solution with an unreactive organic solvent, and includes the steps of:

separating said organic solvent and the product dissolved therein from the aqueous layer which develops during said reaction; and

distilling the organic solvent and product dissolved therein to separate said product from said organic solvent.

No references cited.

TOBIAS E. LEVOW, Primary Examiner P. F. SHAVER, Assistant Examiner 

